So, what's the problem! Read the manual to find out all details on how
to call latex and dvips if you find the above message too cryptic.

I don't find it cryptic at all and this has not been a high priority
item for me but isn't that pointing to a bug in lilypond-book-2.6.0?
Sorry I don't know when I can look at the lilypond-book-2.6.0 code if
that's what's necessary.